Max Planck Institute for Dynamics and Self-Organization

Turbulence in clouds, neuronal fireworks in the brain, the physics of individual cells and the flow of water and oil through porous stone – these, and other particularly complex systems, are the focus of the research carried out by scientists at the Max Planck Institute for Dynamics and Self-Organization. Here, “complex” means that many individual systems combine to form a whole, the dynamics of which cannot necessarily be identified through the behaviour of the individual systems. Scientists say that these systems “organise themselves”. This holds true for the interaction of neurons in the brain (for example during learning) as well as for the numerous swirls that combine to form a turbulent cloud. There is reason to hope that a better understanding of the latter will enable a more accurate prediction of the future influence of clouds on global climate.

Turbulence is omnipresent: it plays an important role during planet formation, mixes fuel and air in the cylinder of an engine, but also increases the energy needed for pumps to push oil through pipelines. Björn Hof and his team at the Max Planck Institute for Dynamics and Self-Organization in Göttingen investigate the finer points of how it originates and search for tricks to prevent the eddies from forming where they interfere.

New forms and sources of energy need new power lines as well. In the future, a larger number of small, distributed wind and solar installations in place of a smaller number of large power plants are projected to supply Germany with energy. At the Max Planck Institute for Dynamics and Self-Organization, the Network Dynamics Group headed by Marc Timme is investigating how the high-voltage grid will respond to this and how it can be optimized.

The effect of branched flow explains how even minute fluctuations in the ocean depth can focus the energy carried by a tsunami wave. A tsunami wave can focus the energy of a seaquake in certain directions where it causes devastating destruction. Current research from the Max Planck Institute for Dynamics and Self-Organization shows that minute fluctuations in the ocean depths can lead to focusing effects and generate strong height fluctuations in the tsunami wave. This formation of a branched flow has severe implications on the way we have to think about predicting tsunamis.

Active and directed fluid transport are crucial for the survival of eukaryotic organisms. This is often carried out by ciliated tissues e. g., the inner wall of the ventriclar system in the mammalian brain. Using a novel method the complexity of the cilia driven fluid flow in the third ventricle of the brain is revealed. Furthermore, ciliated tissues, which are capable of driving such complex flows are interesting for synthetic biology and applications in technology. Therefore, our working group at the MPI for Dynamics and Self-Organization currently attempts to rebuild such ciliated carpets.

The complex structures which emerge when a fluid invades a porous medium are of great relevance for many problems in the geosciences as well as in technology, engineering, and everyday life. Nevertheless, about fifty years of intense research have not been able to identify the dominant mechanisms at work. We have recently found that the solution is much simpler than anticipated. The mechanism is well hidden, but so elementary that high-school math is sufficient to come up with quantitative predictions.

Today's biodiversity is the result of a long-lasting process of origination and extinction of species. The history of this process can be explored by fossil databases. A new mathematical model for the network of dependencies between species helps to improve our understanding of the mechanisms of this process. For instance, the model can explain in which circumstances the extinction of a single species may initiate a mass extinction, and why the growth of the biodiversity on land and in the sea has been qualitatively different from each other.

The dynamics of networks determines our lives. From biochemical reactions in cells and neural circuits in the brain to networks of social contacts and the power grid − all these are networks of units that generate complex emergent functions through multiple nonlinear feedback. Yet we do not understand them. Researchers are now breaking new ground on the way to a future “science on the dynamics of complex networks”, a unique cross-disciplinary enterprise that cannot be captured by individual traditional subjects such as physics or biology, engineering or social sciences alone.